Useful cheap small tester...

[Nick]

Being fair to Peak Electronics (and Fluke) you are comparing apples and pears...

The Peak & Fluke instruments are precision, laboratory grade, devices which can be UL-certified and have guaranteed accuracy.

This unit is probably fine for most hobby use, but no professional EE I'm aware of would rely on it in a lab - at home, maybe...

Most people on this forum deal in components with a nominal tolerance of between 10% and 20% (possibly more) - maybe, rarely, 5%.

In a lab where you need guaranteed accuracy of < 1%, temperature insensitivity, stability over time etc. units like this cheap one simply won't do - piling it high and selling cheap doesn't work.

Apples vs. Pears

[pwdrive]

There's no gaurenteed accuracy with expensive stuff either if it's not regularly calibrated by some certified body.

Lawrence.

[Nick]

There's no gaurenteed accuracy with expensive stuff either if it's not regularly calibrated by some certified body.

...but at least that option is available...

[camallison]

At that price, I've now ordered one - thanks for the dimensions David. I already have an ABS enclosure it will fit nicely into. My use is purely amateur and fine tolerances and accuracy aren't too important to me.

Colin

[Yorkie]

Personally, I'm not putting rockets into space and I'm not in a lab - I'm in 'Granddad's shed'. Any marginal benefit that I might gain from using big name test gear is subjective and would not justify the significant additional cost. Same applies to such things as 'scopes. I simply don't need a complex digital storage scope, so I steer well clear of such things. My Hameg 203-7 analogue scope is just fine for my needs.

I mostly work on stuff which had component tolerances of +/- 10 - 20%, which was originally tested using very basic test gear such as 1,000 OPV Avo Model 7s or 20,000 OPV Model 8s.

A lot of my test gear over the years has been homebrew including my first 'scope and has been adequate for my needs, and the 200 MHz frequency counter I built in 1976 still serves me well. Really, it defies common sense that I still add to my test gear as I've got multimeters all over the place, and several bits of test gear to measure capacitance and inductance including a homebrew PW bridge made years ago (1992). I guess I must have OCD or some such thing!

[Yorkie]

I'll build it into a little box with ......

Perhaps you could make a batch while you're at it

Alan

Huh, not enough hours in the day Alan - we hardly ever seem to be at home!

The gestation period for things on my 'to do' list gets longer each year. Back in 1985 when I was still interested in amateur radio, I built a PW FET Dip Oscillator, and the same author designed a high impedance MOSFET Voltmeter in Dec 1986 PW which I thought would be useful to peak up tuned circuits without loading the circuit. So, I copied the article and made a PCB. I then looked out for a 100uA meter movement as the 2" square one used in the design was in my view far too small. The years went by, then eventually I saw an excellent Ernest Turner meter 5" x 4" at a rally for just £1.00.

So, the PCB and meter were put aside with the article, and I recently decided that I'd make up the PCB and make a little comb-jointed box in which to build the meter. That's as far as it's got - now the summer is here, other priorities will almost certainly take over, so it will most likely become a 'winter project'. I've utterly lost interest in amateur radio, so really I have little need for the meter - it's just another example of my urge to build little homebrew projects - a bug that bit me way back in the late 1940s as a schoolboy and has never really waned since.

Rather than take this thread off topic, I'll post a few pics on progress to date (such as it is), in a thread in the homebrew section.

[Joe]

Look forward to reading it.

- Joe

[Skywave]

A lot of my test gear over the years has been home-brew . . . . . . etc., etc. . . . . I guess I must have OCD or some such thing!

Then that makes two of us!

Yes, I do have a few items of test gear that come into the 'professional laboratory' category: most of these were acquired relatively cheaply by virtue of years of employment in various electronics firms: they had either been deemed B.E.R., redundant, of even salvaged from the skip! However, those few items aside, there is something rewarding & emotionally satisfying in meeting a 'test need' by designing and / or constructing an item that is home-brew: you can include only those features that you want (and omit those that you don't), and you can choose the construction such that future maintenance will not be a headache! For me, even if the finished article, in terms of cost, is comparable to a 'ready-made' commercial item, those considerations carry a lot of weight. Then there are those situations where what is wanted (to meet a need) is simply not available, and such items are occasionally quite simple affairs.

As for calibration and precision (these two are not the same, although they are often regarded as synonymous), of home-brew items, I take a similar attitude to David: will the finished article meet my needs in those two categories? Only today I have been tinkering around with a home-brew d.c. PSU 'add-on' in which it is necessary to monitor (and be able to adjust) the d.c. current output from it. Such is the intended purpose of this item that an indication of 300 mA ± 10 mA will be perfectly adequate. For this monitoring, I simply re-scaled an ancient moving-coil milliammeter (salvaged from the ubiquitous 'junk box') and added a suitable shunt. To calibrate it, I simply used two Fluke DMMs, an AVO 8 and a Phillips DVM, all connected in series with the meter. Those 4 items of test kit all read very nearly the same when 500 mA was flowing: the differences were insignificant. If the differences had been of a relative significance to the requirement, I would have taken the mean value of those separate indications. Hence, the resultant calibration of my 'monitoring meter' will be quite adequate for the need. When this item is finished, I may do a write-up about it and present same here: but, in the meantime, don't hold your breath!

Al.

[Yorkie]

I've now finished my meter, and have attached a few pics. It was a bit fiddly to make an extender for the push button as the movement is only 0.5mm when you press the button so I turned an 'extender' from black plastic rod, which had a hollow to fit over the push button switch on the PCB, and a 'shoulder' to locate it beneath the front panel. (0.5mm too tight in height would have meant the botton was permanently depresssed (and me too!).

I mounted the meter on spacers on a sub panel then screwed that to the front panel.

To connect the three test sockets I just pushed wires into the little test sockets on the PCB, and wired them to the front panel sockets.

I've attached a few pics showing tests of an electrolytic cap, where you can see the actual capacitance and the ESR; a 1K resistor (999R indicated - within 0.1%!); a diode; an RF choke - where it displays both the inductance and resistance, and ancient NOS OC71 transistor, where it indicates what it is (PNP), and the HFE (shown as 'B' - Beta).

For any components other than transistors, the component under test can be connected to any two of the three test points, any polarity, and for transistors, they can be connected to the three test points in any order. The display indicates polarty of caps/diodes, and the connections (ECB) of the transistor. I've got several other test meters for capacitance, inductance, resistance, ESR, and a Peak Electronics Transistor tester. They all give very similar results to this one, and to each other.

Remarkable value for money - gives the battery test, then tests the component, gives the readout, then auto shuts off after 20 secs.

What's not to like?

That's two projects finished in one week - I'm on a roll!

[pwdrive]

Proper job and very handy David, saves a lot of bench clutter and time.

Lawrence.